| 摘要 |
A polysaccharide is converted to a water-insoluble derivative, which is then degraded by hydrolysis sufficiently to obtain a material capable of forming a stable suspension in an aqueous medium upon mechanical attrition. The degraded water-insoluble derivative may be mechanically disintegrated to particles of colloid-forming size. Specified polysaccharides are cellulose, amylose, chitin, xylan and mannan. The water-insoluble derivatives, prepared by known methods, include ethers, esters, thiourethanes, and oxidation products. Many derivatives are listed. The D.S. of the derivative is so chosen that the product is water-insoluble. Hydrolysis of the derivatives may be effected by acids or enzymes. Mechanical attrition or disintegration of the hydrolysed derivative may be carried out by milling, cutting or by subjection to pressure. The attrition may be carried out in presence of water, an alcohol, e.g. ethanol, iso-propanol or glycerol, or a sugar solution. The liquid medium may be omitted when attrition is effected by pressure. The products of the invention, forming stable colloidal dispersions or thixotropic gels which are resistant to syneresis or bacterial attack, may be used as food additives, pharmaceutical and cosmetic carriers, and fillers for moulding resins. Examples relate to the hydrolysis and mechanical disintegration of hydroxypropyl and hydroxyethyl cellulose, and cellulose triacetate. Specification 874,945 is referred to. |
